MIT Researchers Find A Way To Provide Cooling Without Power

The new passive system could be used to preserve food and medications in hot, off-grid locations.

Using inexpensive materials, MIT researchers have devised a new way of providing cooling for structures. The new passive system that works without power could one day be used to supplement other cooling systems and to preserve food or vaccines in hot, remote locations. The system is essentially a high-tech version of a parasol that radiate heat in the form of mid-infrared wavelengths of light and enables it to pass straight out through the atmosphere.

Most existing cooling devices such as air conditioners are expensive and consume a lot of energy. An alternative to these extremely energy-inefficient systems is passive system which spontaneously cools a surface by reflecting sunlight and radiating heat to the colder atmosphere. Although other groups have attempted to design passive cooling systems, they mostly involve complex photonic devices that cannot be readily available for widespread use.

The new system is remarkably simple, based on a combination of inexpensive materials like plastic film, polished aluminum, white paint and insulation. Then, it has a small strip of metal on its top to block direct sunlight. The device could lead to more efficient, environmentally-friendly temperature control in the future.

“We built the setup and did outdoors experiments on an MIT rooftop,” said research scientist Bikram Bhatia. “It was done using very simple materials.”

Researchers carried out extensive tests to prove the effectiveness of the system. So far, in the initial testing, they have achieved a cooling of 6 degrees Celsius, but they believe that an improved version could provide cooling of as much as 20 degrees Celsius (36 degrees Fahrenheit). By shading the device with an umbrella and supplementing it with insulation, researchers made passive cooling more viable.

“It’s kind of deceptively simple,” said researcher Evelyn Wang. “By having a separate shade and an emitter to the atmosphere – two separate components that can be relatively low-cost – the system doesn’t require a special ability to emit and absorb selectively. We’re using angular selectivity to allow blocking the direct sun, as we continue to emit the heat-carrying wavelengths to the sky.”

While most other passive systems focus on cooling entire rooms or buildings, the new approach is localized.

“This would be useful for refrigeration applications, such as food storage or vaccines,” said Wang. “It could at least reduce the loads on the electrical refrigeration systems, to provide just the final bit of cooling.”

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Hira BashirThe latest discoveries in science are the passion of Hira Bashir (Google+). With years of experience, she is able to spot the most interesting new achievements of scientists around the world and cover them in easy to understand reporting.